Optionally avoid custom node errors.

Custom node errors, when shown directly, obscure the
real cause of the error by only showing it in the handled
exception's traceback. By default, don't raise the custom error
but the original one.

However, still allow the user to request the custom error to
be raised, because it contains useful information like the node
that errored and which inputs was using.

src/sisl/nodes/context.py

@@ -9,7 +9,11 @@
     # On initialization, should the node compute? If None, defaults to `lazy`.
     lazy_init=None,
     # The level of logs stored in the node.
-    log_level="INFO"
+    log_level="INFO",
+    # Whether to raise a custom error exception (e.g. NodeCalcError) By default 
+    # it is turned off because it can obscure the real problem by not showing it
+    # in the last traceback frame.
+    raise_custom_errors=False,
 )
 
 # Temporal contexts stack. It should not be used directly by users, the aim of this

src/sisl/nodes/node.py

@@ -90,6 +90,8 @@ class Node(NDArrayOperatorsMixin):
     # Whether the node has errored during the last execution
     # with the current inputs.
     _errored: bool
+    # The error that was raised during the last execution
+    _error: Optional[NodeError] = None
 
     # Logs of the node's execution.
     _logger: logging.Logger
@@ -133,6 +135,7 @@ def setup(self, *args, **kwargs):
 
         self._outdated = True
         self._errored = False
+        self._error = None
 
         self._logger = logging.getLogger(
             str(id(self))
@@ -370,12 +373,18 @@ def get(self):
                 self.logs += logs.stream.getvalue()
                 logs.close()
                 self._errored = True
-                raise NodeCalcError(self, e, evaluated_inputs)
+                self._error = NodeCalcError(self, e, evaluated_inputs)
+
+                if self.context['raise_custom_errors']:
+                    raise self._error
+                else:
+                    raise e
 
             self._nupdates += 1
             self._prev_evaluated_inputs = evaluated_inputs
             self._outdated = False
             self._errored = False
+            self._error = None
         else:
             self._logger.info(f"No need to evaluate")